Constant-Thrust Device Eliminates Pipeline Thermal Walking
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Solution Overview
Problem
High-temperature and high-pressure subsea pipelines experience thermal walking due to thermal transients and asymmetric loads, which existing restraints, such as anchors and piles, are costly and inefficient in deep water, and often impractical in shallow water, leading to significant horizontal loading on foundations.
Innovation Solution
A subsea constant-thrust device is interposed between a pipeline and its foundation to apply a near constant axial force, using a piston-in-cylinder arrangement driven by external hydrostatic pressure, reducing horizontal loading and eliminating thermal walking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anchors or piles are used to restrain pipeline thermal walking in deep water, then thermal walking is prevented, but cost and installation complexity increase significantly
Solution Approach 1:
The patent employs a dynamic restraint system where the pipeline is allowed to move vertically and horizontally within certain limits through a floating structure, eliminating the need for rigid anchors and piles. The system adapts to thermal expansion and contraction dynamically rather than resisting it with fixed structures.
Solution Approach 2:
A floating structure serves as an intermediary between the pipeline and the seabed, providing thermal walking restraint without direct contact between the pipeline and anchor piles. This mediator absorbs and distributes the thermal forces, reducing the complexity of the restraint system.
2Stability of the object's composition
If rigid foundations are used to restrain pipeline movement, then pipeline position is stable, but horizontal loading on the foundation increases significantly
Solution Approach 1:
The system transitions from a static rigid foundation to a dynamic floating structure that moves with the pipeline during thermal transients. This dynamic approach maintains pipeline stability while significantly reducing the horizontal forces transmitted to the foundation.
Solution Approach 2:
The patent changes the operational parameters of the restraint system by allowing controlled movement rather than complete rigidity. The floating structure adjusts its position based on thermal conditions, transforming the force transmission characteristics and reducing peak loads on the foundation.
3Stability of the object's composition
If pipeline thermal expansion is fully restrained, then pipeline position is controlled, but thermal stresses in the pipeline increase
Solution Approach 1:
The floating restraint system provides dynamic control rather than rigid restraint, allowing the pipeline to expand and contract thermally while maintaining overall position control. This dynamic approach significantly reduces thermal stresses compared to fully restrained systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The constant-thrust device effectively eliminates thermal walking while reducing the load on foundations, potentially eliminating the need for costly anchors and piles, and allowing for more efficient subsea pipeline architecture.
Implementation Method 1
using a piston-in-cylinder arrangement driven by external hydrostatic pressure
Data Source
AI summary
The invention is a means to eliminate thermal or pressure walking of a pipeline by applying a constant axial force to the pipeline through the interposition of a constant-thrust device between a point fixed to the pipeline and a point on a foundation, which pair of points are otherwise unconstrained relative to each other in the longitudinal direction of the pipeline.